Effect of heat input on microstructure and mechanical properties of the high strength aluminum alloy welds

2519 high strength aluminum alloy was welded with metal inert-gas welding process, and the effect of heat input on the microstructure, mechanical properties and fracture characters of the welds were studied.Results indicate that with the increase of the heat input, the second dendrite arm spacing increase and the content of solute in dendrite core decrease.After aging, the number of θ' phase decrease, but its size increase.And the morphology of the eutectic phase changes from low rod type to long band network type with the increase of heat input, which causes the fracture type from trasngrannular to intergrannular.The tensile strength reduces greatly with the increase of heat input, and the improvement of tensile strength is greater under low heat input condition after aging treatment.